Viperinae, Oppel, 1811

Ivanov, Martin, 2000, Snakes of the lower / middle Miocene transition at Vieux Collonges (Rhône, France), with comments on the colonisation of western Europe by colubroids, Geodiversitas 22 (4), pp. 559-588 : 583-584

Viperinae A

Viperinae A – Ivanov 1997a: 147, fig. 68.

MATERIAL EXAMINED. — 12 trunk vertebrae ( FSL 369451- FSL 369462).

DESCRIPTION

Trunk vertebrae ( Fig. 15 )

All vertebrae are fragmentary. In lateral view, the neural spine is relatively low (about three times longer than high). Both its cranial and caudal

A B C

margins are inclined caudally. The interzygapophyseal ridges are conspicuous. Small but distinct lateral foramina may occur in shallow depressions. The subcentral ridges are well-developed. The para- and diapophyses, mostly broken off, are well-separated from each other. The parapophyseal processes are directed distinctly anteroventrally. The hypapophyses are broken off at the base. In dorsal view, the zygosphenal lip is generally crenate with distinct lateral and median lobes, the zygosphene is not usually straight. The damaged prezygapophyseal articular surfaces were most probably oval, the prezygapophyseal processes are always broken off at the base. Epizygapophyseal spines are lacking. The condyle is considerably large. In ventral view, the anterior keel of the hypapophysis expands triangularly, distinct subcotylar tubercles occur below the ventral margin of the cotyle in some cases. The subcentral ridges are mostly not prominent, the subcentral grooves are wide and very shallow. The subcentral foramina are well-visible and situated at the base of the hypapophysis. In cranial view, the neural arch is strongly flattened dorsoventrally, the neural canal is subcircular with lateral sinuses. The zygosphenal lip is convex. The prezygapophyses are tilted upward. Very large paracotylar foramina occur in depressions on both sides of the rounded to slightly dorsoventrally flattened cotyle. The metrical measurements of the largest vertebrae are as follows (n = 5): cl: or = 3.34-4.51; naw: or = 2.30-3.05; cl/naw: or = 1.32-1.51, mean 1.43 + 0.07.

DISCUSSION

The vertebrae belong to the family Viperidae and to the subfamily Viperinae which is demonstrat- ed by the dorso-ventrally strongly flattened neural arch and antero-ventrally directed parapophyseal processes. The vertebrae have relatively high ratio cl/naw and the low neural spine which represents the basic criterion for the affiliation to the “European vipers” group. The neural spine is not so extremely low as it is in case of representatives of the complex “ berus ”, therefore, it is assumed that these vertebrae belong to the representatives of the complex “ aspis ” (Szyndlar 1991a). This is also supported by the fact that the ratio cl/naw is lower, in case of the representatives of the complex “ aspis ”, in comparison with the representatives of the complex “ berus ” where the ratio is higher. Thus, the presupposed (Szyndlar & Rage 1999) occurrence of the “ aspis ” group at Vieux Collonges is supported.

Figures

FIG. 15. — Viperinae A from the lower/middle (MN 4/5) Miocene of Vieux Collonges, trunk vertebra (FSL 369457); A, lateral view; B, dorsal view; C, ventral view; D, cranial view; E, caudal view. Scale bar: 2 mm.